Scroll Into View Repeat Regression

Report

Route: http://localhost:3100/examples/scroll-into-view

Steps:

1. Type at the end of the editor while scrolled away from the caret.
2. The editor autoscrolls to the caret.
3. Scroll up again.
4. Type again.

Expected: the editor autoscrolls again.

Actual: the second typed update does not autoscroll.

Investigation

• Relevant source owner: .tmp/slate-v2/packages/slate-react/src/components/editable.tsx.
• defaultScrollSelectionIntoView temporarily assigns leafEl.getBoundingClientRect so scroll-into-view-if-needed measures the focus point.
• Current cleanup sets leafEl.getBoundingClientRect = undefined, which shadows the prototype method on the same DOM node. A later scroll attempt sees typeof leafEl.getBoundingClientRect !== 'function' and returns early.
• Related learning: docs/solutions/logic-errors/2026-04-20-editable-blocks-app-owned-surfaces-must-not-churn-runtime-ids-or-miss-plain-editor-updates.md says selection-to-DOM scroll forwarding needs focused contracts.

Plan

• Add a focused regression test proving the default scroll helper preserves the leaf element measurement function across repeated calls.
• Fix cleanup to restore the previous element measurement behavior instead of poisoning the element.
• Verify with focused slate-react tests, typecheck, lint, and Browser route coverage on the reported route.

Result

• defaultScrollSelectionIntoView now restores the original leaf measurement behavior after temporary focus-point measurement.
• Added a regression test covering the poisoned leaf-element case.
• Added a slate-react patch changeset.

Verification

• bun test ./packages/slate-react/test/editable-behavior.tsx -t "default scroll restores leaf measurement" passed after fix.
• bunx biome check packages/slate-react/src/components/editable.tsx packages/slate-react/test/editable-behavior.tsx --fix passed.
• bun test ./packages/slate-react/test/editable-behavior.tsx passed.
• bun test ./packages/slate-react/test/rendering-strategy-and-scroll.tsx ./packages/slate-react/test/editable-behavior.tsx passed: 37 tests, 153 expects.
• bun --filter slate-react typecheck passed.
• pnpm lint:fix in plate-2 passed.
• bun run completion-check in plate-2 passed with no session state.
• Browser was used on http://localhost:3100/examples/scroll-into-view to load the reported surface and exercise the scrollable editor. Browser coordinate control was not reliable enough to place the caret at the lower text endpoint; the exact repeated-scroll failure is covered by the focused DOM-range regression test.